1. Field of the Invention
The present invention relates to optical devices in general and in particular to an improved method and apparatus for performing optical logic and switching functions.
2. Description of Background
Optical logic and switching devices commonly include semiconductor components which are electrically biased to achieve proper processing of optical signals impinging on the semiconductor components. These electrooptical devices exhibit various disadvantages. Most significantly, electrooptical logic and switching devices have speed limitations associated with the RC time constant of the electrodes, and in addition experience energy losses as a result of the electrical to optical conversion process.
Recently, proposals have been made for the design of "all-optical" logic gates and switches. For example, U.S. Pat. No. 4,881,788 to Doran discloses an optical device wherein coupled signals are split and propagated along first and second optical fibers having equal lengths but different material properties. Signals propagating through the fibers arrive synchronously but phase shifted at a coupler connected at the terminal end of the fibers, and logic or switching operations are realized by detection of the phase shift. In a device described in U.S. Pat. No. 4,932,739 to Islam, a pair of optical signals are propagated in a birinfringent fiber to induce soliton trapping between the signals, and logical operations are realized by detection of effects resulting from the trapping. The above designs suffer from numerous limitations including high switching power, environmental instability, and long latency time.
There exists a need for a method and apparatus for providing all optical logic and switching functions which does not exhibit the disadvantages inherent in the prior art devices.